Chronic diarrhea pathophysiology
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Chronic diarrhea Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Omodamola Aje B.Sc, M.D. [2]
Overview
Pathophysiology
The fundamental pathophysiology of all diarrhea is incomplete absorption of water from the lumen either because of a reduced rate of net water absorption (related to impaired electrolyte absorption or excessive electrolyte secretion) or because of osmotic retention of water intraluminally.[1] The causes of chronic diarrhea include inflammatory, osmotic, secretory, iatrogenic, motility, and functional diseases. In general, no single cause of chronic diarrhea is truly unifactorial from a perspective of pathophysiology. For example, cholera is caused by secretion and altered motility[2] whereas pseudomembranous colitis is said to be associated with secretion, inflammation, and motility[3].
Thus, diarrhea is a condition of altered intestinal water and electrolyte transport. The pathophysiologic mechanisms of diarrhea include osmotic, secretory, inflammatory, and altered motility.
- Osmotic chronic diarrhea; involves an unabsorbed substance that draws water from the plasma into the intestinal lumen along osmotic gradients. Examples of chronic diarrhea due to an osmotic cause include malabsorption states such as celiac disease, bacterial overgrowth, osmotic laxatives and maldigestion as occurs commonly in disaccharidase deficiency, and pancreatic exocrine insufficiency. Osmotic diarrheas might result in steatorrhea and azotorrhea (passage of fat and nitrogenous substances into the stool), but typically they do not cause any rectal bleeding.[4]
- Secretory chronic diarrhea results from disordered electrolyte transport and, despite the term, is more commonly caused by decreased absorption rather than net secretion. Examples of secretory diarrheas include congenital abnormalities such as congenital chloridorrhea, in which an abnormality in the genetic control of chloride-bicarbonate exchange in the ileum results in the loss of chloride into the stool. Another example is the loss of α2-adrenergic function in enterocytes of patients with autonomic neuropathy caused by diabetes mellitus. The typical features of secretory diarrhea include the persistence of the diarrhea with fasting and the absence of steatorrhea, azotorrhea, or blood per rectum.[5] Secretoty diarrheas caused by neuroendocrine tumors has been identified by measurement of plasma levels of the hormone or its metabolite in the urine. Examples include measurements of VIP, gastrin, or calcitonin in plasma or 24-hour collections of urine for 5-hydroxyindoleacetic acid.[5]
- Inflammatory chronic diarrhea diseases cause diarrhea with exudative, secretory, or osmotic components.
- Altered motility of the intestine or colon may alter fluid absorption by increasing or decreasing the exposure of luminal content to intestinal absorptive surface.
- Iatrogenic causes of chronic diarrhea
However, from a pathophysiologic perspective, no single cause of diarrhea is truly unifactorial.
Pathogenesis
References
- ↑ Sweetser S (2012). "Evaluating the patient with diarrhea: a case-based approach". Mayo Clin Proc. 87 (6): 596–602. doi:10.1016/j.mayocp.2012.02.015. PMC 3538472. PMID 22677080.
- ↑ Goyal RK, Hirano I (1996). "The enteric nervous system". N Engl J Med. 334 (17): 1106–15. doi:10.1056/NEJM199604253341707. PMID 8598871.
- ↑ Kurose I, Pothoulakis C, LaMont JT, Anderson DC, Paulson JC, Miyasaka M; et al. (1994). "Clostridium difficile toxin A-induced microvascular dysfunction. Role of histamine". J Clin Invest. 94 (5): 1919–26. doi:10.1172/JCI117542. PMC 294602. PMID 7962537.
- ↑ Morris AI, Turnberg LA (1979). "Surreptitious laxative abuse". Gastroenterology. 77 (4 Pt 1): 780–6. PMID 467934.
- ↑ 5.0 5.1 von der Ohe MR, Camilleri M, Kvols LK, Thomforde GM (1993). "Motor dysfunction of the small bowel and colon in patients with the carcinoid syndrome and diarrhea". N Engl J Med. 329 (15): 1073–8. doi:10.1056/NEJM199310073291503. PMID 8371728.